Effect of Freeze/Thaw Cycles on the Performance and Microstructure of Cement-Treated Soils

In this paper, the performance and structural changes in cement-treated soils under influence of freeze/thaw (f/t) exposure are investigated. Specimens from plastic and compacted soil-cement mix designs were exposed to different f/t scenarios to study the influence of f/t dimensionality (i.e.,one-dimensional versus three-dimensional exposure) and specimens' age at the time of f/t exposure on changes in their performance. Changes in hydraulic conductivity, unconfined compressive strength, and longitudinal resonant frequency of the specimens were studied under each exposure scenario. An examination of the microstructure of the f/t exposed and control specimens using transmitted light optical microscopy was also performed to evaluate how the soil-cement matrix was disrupted after exposure to f/t cycling. Observations showed increases in water content of the mix design (when wet of optimum water content), as well as increased specimen age at the time of exposure may increase f/t susceptibility. On the other hand, comparison of the performance of the specimens exposed to 1D and 3D f/t exposure did not show any significant variation. Microstructural analysis of petrographic thin section samples from control and f/t exposed specimens showed that while optical microscopy can detect matrix disintegration for highly damaged specimens, it is not able to identify structural degradation at early stages of damage development.